United Kingdom patent application No. 2071650 published Sept. 23, 1981 describes monocyclic .beta.-lactam antibiotics having a sulfonic acid salt substituent in the 1-position of the .beta.-lactam nucleus and an acylamino substituent in the 3-position of the .beta.-lactam nucleus.
U.S. Pat. No. 4,610,824 describes beta-lactams having the formula ##STR2## wherein R.sub.1 and R.sub.2 are each independently hydrogen or alkyl of 1 to 4 carbon atoms, or R.sub.1 and R.sub.2 together with the carbon atom to which they are attached form a cycloalkyl ring;
R.sub.3 is hydrogen or alkyl; PA0 R.sub.4 is hydrogen or alkyl, and R.sub.5 can be phenylcarbonyl or substituted phenylcarbonyl.